尿素

尿 = 尸 + 水 : Nefertiti (ni) is drinking from a water fountain (水) in the aorta's bathroom (ao4), but she doesn't notice that at the same time a ghost (尸) is peeing (尿) into the water fountain.

素 = 龶 + 糸 : Susan Saint Bernard (su) has decided to become a vegan (素) and to let everyone know. In the space station's bathroom (Ø4) she manufactures a fancy headdress (龶) in the form of a vegan flower (素) out of her own spider silk (糸) so that everyone who sees her instantly knows that she's vegan (素).